Reduce the size of the above-the-fold content

This rule triggers when PageSpeed Insights detects that additional network round trips are required to render the above the fold content of the page.

Overview

If the amount of data required exceeds the initial congestion window (typically 14.6kB compressed), it will require additional round trips between your server and the user’s browser. For users on networks with high latencies such as mobile networks this can cause significant delays to page loading.

Recommendations

To make pages load faster, limit the size of the data (HTML markup, images, CSS, JavaScript) that is needed to render the above-the-fold content of your page.
There are several ways to do this:

Structure your HTML to load the critical, above-the-fold content first

Load the main content of your page first. Structure your page so the initial response from your server sends the data necessary to render the critical part of the page immediately and defer the rest.
This may mean that you must split your CSS into two parts: an inline part that is responsible for styling the ATF portion of the content, and the part that can be deferred.

Consider the following examples of how a site could be restructured to load faster:

If your HTML loads third-party widgets before it loads the main content, change the order to load the main content first.

If your site uses a two-column design with a navigation sidebar and an article, but your HTML loads the sidebar before the article, consider loading the article first.

Reduce the amount of data used by your resources

Once your site has been redesigned to work well across multiple devices and load the critical content first, use the following techniques to reduce the amount of data required to render your page:

Minify Resources: HTML, CSS, and JavaScript can be minified by removing unnecessary whitespace and comments. Further optimizations may be possible through the use of tools which rename variable names in your resources.